Ultrasound is a non-intrusive diagnostic technique originally developed in the late 1950's. Using very high frequency sound waves, echo images are produced that are particularly useful for imaging many of the internal structures of living organisms. In recent years, the quality of ultrasound equipment has been improved and the equipment is now capable of producing images of outstanding detail and clarity. Unlike x-rays, ultrasound produces dynamic views which are especially useful in examining concealed structures which are subject to changes in shape or position, such as the human heart, human fetuses, the circulatory system and reproductive and internal organs. An ultrasound examination is generally referred to as a "scan", and will be so referred to in this document.
Traditionally, ultrasound scans have been stored on analog media as video images using a video cassette recorder to record the images on a video cassette tape. Those tapes are reviewed by physicians for diagnosis and are generally kept for reasons of clinical history and medical liability. It is well known that video tape has a long but limited shelf life. It is also known that the quality of video tape reproduction deteriorates over time. Furthermore, video tape is voluminous and requires substantial storage space. There are also other disadvantages associated with storing ultrasound images on video tape. For example, reviewing video tape must be done in a linear progression. In order to locate a particular sequence on the tape, the tape must be viewed sequentially, fast forwarded or rewound until the frames of interest are located. Besides, even with expensive video cassette recorders, still frames are generally of poor quality so that details shown in only a few frames may be difficult to detect and/or analyze for purposes of diagnosis. It is also difficult to annotate an ultrasound video recording since the only annotations that can be made during recording are voice recordings made by the sonographer or a physician present during the recording process. For many reasons, including the presence of the patient, the sonographer's ability to comment during an ultrasound scan is limited. Any observations made by the doctor after recording an ultrasound scan must be recorded on a separate medium and linked to the video tape as annotations using a video tape counter, which may be less accurate than desired if the video is later reviewed using a different video cassette recorder.
Hospitals are currently under pressure to operate more efficiently while improving the quality of care they provide. While ultrasound has become an increasingly important tool in assuring quality of care, the burden of capturing, recording and storing ultrasound images has not been much facilitated for many years. The current volume of usage of ultrasound as a diagnostic tool has made that burden onerous. Many vendors of ultrasound equipment now provide still frame and three second "cine loop" storage and display in order to facilitate diagnosis but there remain many problems associated with the capture and storage of ultrasound images. For example, technologists often waste time locating a patient's video tape and then spend more time winding the tape to a free recording space. After an ultrasound session is recorded, it must be reviewed by a physician for diagnosis, and reported. Reports are generally dictated by the physician and then typed by a transcriptionist. This requires time and skilled support staff, and introduces the possibility of stenographic and typographic errors.
There therefore exists a need for an improved, more versatile system of recording, storing and reviewing ultrasound images particularly ultrasound images used in clinical diagnoses in hospital environments.